The invention relates to a method for guiding the movement of a movable machine element of a machine, and to a corresponding control device.
Machines such as, for example, machine tools, production machines and/or robots frequently require a movable machine element to be positioned exactly, free from vibration and as quickly as possible. A movable machine element cannot be positioned free from vibration and optimally in terms of time by adjustment with the aid of a simple desired stipulation using a controller for moving the machine axes as a function of a prescribed travel path and prescribed dynamic parameters. Depending on the current load, the path length and the parameters set for jerk, acceleration and speed, when the machine element is being positioned more or less large vibrations of the machine element and/or of a load occur and can be avoided only with difficulty.
Vibrations of the load increasingly occur in the case of production machines in the form of loading and unloading devices, in particular.
The prior art discloses various optimization methods for guiding the movement of a movable machine element that enable appropriate movement profiles, for example time-optimized traveling, that is to say traveling of the machine element and/or the load at the highest possible speed and, in the process, keep the vibrations that occur in the machine element and/or the load in an acceptable range. However, such methods can be used to calculate virtually nonvibrating movement operations, the latter then being no longer time-optimized as a rule, that is to say the travel movement is carried out more slowly.
Such optimization methods are, however, sufficiently well known to the person skilled in the art from German laid open patent applications DE 100 63 722 A1, DE 102 00 680 A1 and DE 103 15 525 A1, which are intended to be valid as a constituent of the disclosure of this application. One or more natural frequencies of the machine axes to be moved can be suppressed with the aid of the above-described optimization methods. Generally speaking, the basic idea applies here, at least in principle, that the less the travel movement is to be implemented with vibrations, the less the movement can be carried out in a time-optimized fashion, that is to say less quickly, and vice versa.
All these optimization methods known from the prior art are not carried out commercially on a control device for controlling the machine, but they are carried out in advance by the user on a computing device outside the machine such as, for example, a personal computer. Commercially speaking, in this case the travel movement to be executed is input into the external computer (for example in order to move the machine element by 3 m in the X-direction) and the optimization method calculates a correspondingly optimized movement profile.
A movement profile calculated externally in such a way for each machine axis is then used to generate a setpoint variable in the control device for each machine axis of the machine, and to pass it on as desired value to a closed-loop controller for carrying out the travel operation of the movable machine element.
Here, the previously known mode of procedure has the disadvantage that, as already stated, there is firstly a need to calculate the movement profile on an external computer and then to transcribe the calculated movement profile onto the control device of the machine, which then executes the movement in accordance with the movement profile. The user, that is to say the operator of the machine, then no longer has any possibility when on the spot at the machine to influence the travel operation on the spot in a quasi-online fashion directly at the machine with regard to a movement operation, which still exhibits fewer vibrations, or with regard to a time-optimized movement operation, because the load is still vibrating too strongly in the case of the calculated movement profile, for example. To this end, it is firstly necessary commercially to recalculate on the external PC a new movement profile that then needs to be retranscribed onto the control device. Not until then can the movement guidance be carried out with the new movement profile. The previous mode of procedure is therefore very complicated and cost-intensive.
German laid open patent application DE 101 64 496 A1 discloses an automation system for movement guidance in which movement profiles are processed with reference to time and position for the purpose of guiding movement.
German laid open patent application DE 100 65 422 A1 discloses a method and an open-loop controller for compiling and optimizing cam functions.
German laid open patent application DE 100 55 169 A1 discloses a commercially available industrial open-loop controller for production machines, in particular.